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Short-term toxicity to aquatic invertebrates

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short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD guideline study conducted under GLP
according to guideline
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
As noted in the hydrolysis section, oximesilanes quicky hydrolyze to the corresponding oxime and reactive silanols which spontaneously cross link to form high molecular weight silicone polymers. The relevant hydrolysis product is MPKO, the substance that was tested.

Data on selected oximes and oxime silanes are summarized in the attached Table. Although data for each endpoint is not available for all products, the available data show similarities between oxime silanes and their hydrolysis products (oxime). These materials show low toxicity to fish, and daphnia. For algal studies, the toxicity shows a structure activity relationship. The smaller oximes are more toxic to alga, the larger oximes and associated oxime silanes are less toxic. The similarities in response between the oximes and oxime silanes provide additional support of the silicone containing moieties do not contribute to the aquatic toxicity of these materials. Due to the rapid hydrolysis, it is appropriate to use the oxime as surrogate data for t he oxime silane.

Analytical monitoring:
Details on sampling:
The concentrations of methyl propyl ketoxime in the test solutions were measured at 0 and 48 hours using a high performance liquid chromatography with an UV/visible detector
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
A primary stock concentrate of methyl propyl ketoxime, with a nominal concentration of 100 mg/l, was prepared by adding a nominal 0.1 g of test substance to 1 litre of dilution water. The concentrate was then inverted and stirred for 10 minutes. The resultant stock was observed to be clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
- Common name: Daphnia magna
- Source: continuous laboratory cultures held at the laboratory
- Age at study initiation (mean and range, SD): < 24 hours
- Feeding during test - No

Laboratory culture:
- conditions (same as test or not): same
- Type and amount of food: mixed algae diet of Chlorella vulgaris, strain CCAP 211/12 and Pseudokirchneriella subcapitata, strain ATCC 22662; ad libitum
- Feeding frequency: fed daily
Test type:
Water media type:
Limit test:
Total exposure duration:
48 h
Post exposure observation period:
Test temperature:
20 +/- 1°C
7.87 to 7.97
Dissolved oxygen:
9.2 mg/l for both control and test article vessels
Nominal and measured concentrations:
Measured concentrations within 95% of nomimal (98% average). Results reported as nominal values
Details on test conditions:
- Test vessel: Glass beakers of 250 ml nominal capacity
- Fill volume: 200ml
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

- Culture medium different from test medium: no
- Intervals of water quality measurement: time 0 and 48 hours

- Adjustment of pH: no
- Photoperiod:16 hours light:8 hours dark, with 20 minute dusk and dawn transition periods

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : at 24 and 48 hours, daphnia were observed by eye for 15 seconds to determine movement and overt signs of toxicity

- limit test - 100 mg/l
48 h
Dose descriptor:
Effect conc.:
>= 100 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
48 h
Dose descriptor:
Effect conc.:
> 100 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
Details on results:
- Behavioural abnormalities: none
- Other adverse effects control: 1 of 20 were immobile at 48hrs
- Abnormal responses: none observed
Reported statistics and error estimates:
None needed - no immobilization was observed

Table 1: Validity criteria for OECD 202.

Criterion from the guideline


Validity criterion fulfilled

In the control, including the control containing the solubilising agent, not more than 10% of the daphnids should have been immobilized.



The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.

9.2 mg/L




Validity criteria fulfilled:
Please refer to Table 1 at "Any other information on results incl. tables"
MPKO is not toxic to daphnia. No immobilization was observed in daphnia exposed to 100 mg/l MPKO.

Description of key information

EC50 (48 h) >100 mg/L (nominal, OECD 202). 

Key value for chemical safety assessment

Additional information

One study investigating the acute toxicity of 2-Pentanone oxime to aquatic invertebrates is available. The study was performed according to OECD guideline 202 as a limit test (GLP). Daphnia magna were exposed to a limit concentration of 100 mg/L for 48 hours. The substance concentration was analytically verified by HPLC. The measured test substance concentrations were within 98% (average) of the nominal value. Immobilisation of the Daphnids was not observed. Thus, the determined EC50 (48 h) was >100 mg/L (nominal).